Michelle Dresbold, a handwriting expert and author of Sex, Lies and Handwriting, has analyzed documents for the U.S. Secret Service. She said Trump’s signature is very revealing.

She observed that his handwriting is “all angles,” a clear indicator of aggression.

"I always tell people take your hand and make angles and when you do angles what can't you do? You can't relax," she told Inside Edition. "Somebody who makes all angles is intense, competitive, driven, hostile, angry.”

In his signature, Dresbold observed a cross between "Donald" and "Trump" which she claims means “don’t cross me and if you do I’m willing to battle. I'm willing to fight."

Trump presses hard with his pen and his signature is big and bold — just like his personality.

“When somebody presses really hard they are very intense, obsessive. It's an obsessive quality. Also he writes very big and you can see his handwriting. They say, ‘hey look at me! And look at me now,'" she said.

In 2015, Trump sent an angry note to basketball legend Kareem Abdul-Jabbar. It's scrawled across a magazine article written by Jabbar who was critical of Trump, who at the time was campaigning for the White House.

It's written diagonally across the page, not top to bottom.

“What that means is, 'Hey, I am not going to follow the rules of everybody else. I am following my own rules. I am making them up,'" she claims.

In another note, one Trump sent to Vanity Fair in 2011, his method of drawing the letter "I" reveals something surprising, according to Dresbold.

“He has a little lower self-esteem than you would imagine and that he feels that he can never live up to what his father and mother expected out of him,” she said. “On the inside he does not feel like this big shot. He feels very insecure but he overcompensates for it by being overly secure.”